CN109950266A - Imaging sensor and the method for forming imaging sensor - Google Patents
Imaging sensor and the method for forming imaging sensor Download PDFInfo
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- CN109950266A CN109950266A CN201910229743.9A CN201910229743A CN109950266A CN 109950266 A CN109950266 A CN 109950266A CN 201910229743 A CN201910229743 A CN 201910229743A CN 109950266 A CN109950266 A CN 109950266A
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Abstract
This disclosure relates to a kind of imaging sensor, including the first pixel unit, first pixel unit include: the photodiode being formed in semiconductor material layer；Dielectric layer under the semiconductor material layer is set；And the light for passing through the semiconductor material layer being formed in the dielectric layer is directed to the light guide of the photodiode, the bottom surface far from the semiconductor material layer of the light guide is configured as the light for reaching the bottom surface inside the light guide being reflected back inside the light guide, and the side surface of the light guide is configured as the light for reaching the side surface inside the light guide being reflected back inside the light guide.Present disclosure also relates to a kind of methods for forming imaging sensor.The disclosure can be improved the absorptivity of light and reduce the crosstalk of light.
Description
Technical field
This disclosure relates to technical field of semiconductors, it particularly relates to a kind of imaging sensor and formation imaging sensor
Method.
Background technique
Imaging sensor generally includes the multiple pixel units being arranged in array, and each pixel unit includes at least one light
Electric diode.Photodiode is used to convert charge for received light.For the volume or photoelectricity two to imaging sensor
The consideration of the charge-trapping of pole pipe etc., photodiode usually have a desired thickness range.And in these thickness ranges
Photodiode cannot fully absorb incident light sometimes.These unabsorbed light can pass through photodiode and reach other
Component, for example, being located at the metal interconnecting layer etc. under photodiode.The light for reaching metal interconnecting layer is easy to be interconnected by metal
Part reflection.If the light for passing through the photodiode of the first pixel unit is reflected into the second pixel unit and quilt by metal interconnecting piece
Photodiode in second pixel unit absorbs, and will cause optical crosstalk.
Accordingly, there exist the demands to new technology.
Summary of the invention
The method that the first purpose of the disclosure is to provide the new imaging sensor of one kind and forms imaging sensor.
According to the disclosure in a first aspect, provide a kind of imaging sensor, including the first pixel unit, first picture
Plain unit includes: the photodiode being formed in semiconductor material layer；The electricity under the semiconductor material layer is arranged in be situated between
Matter layer；And the light for passing through the semiconductor material layer being formed in the dielectric layer is directed to the photoelectricity two
The light guide of pole pipe, the bottom surface far from the semiconductor material layer of the light guide is configured as will be out of described light guide
The light that portion reaches the bottom surface is reflected back inside the light guide, and the side surface of the light guide is configured as to lead from described
The light that the side surface is reached inside light part is reflected back inside the light guide.
According to the second aspect of the disclosure, a kind of method for forming imaging sensor is provided, comprising: for wherein
It is formed under the semiconductor material layer of photodiode and forms dielectric layer；And it is formed in the dielectric layer for that will wear
The light for crossing the semiconductor material layer is directed to the light guide of the photodiode, the separate semiconductor of the light guide
The bottom surface of material layer is configured as the light for reaching the bottom surface inside the light guide being reflected back in the light guide
Portion, the side surface of the light guide are configured as the light for reaching the side surface inside the light guide being reflected back described lead
Inside light part.
By the detailed description referring to the drawings to the exemplary embodiment of the disclosure, the other feature of the disclosure and its
Advantage will become apparent.
Detailed description of the invention
The attached drawing for constituting part of specification describes embodiment of the disclosure, and together with the description for solving
Release the principle of the disclosure.
The disclosure can be more clearly understood according to following detailed description referring to attached drawing, in which:
Fig. 1 is the signal for schematically showing the structure of imaging sensor of some exemplary embodiments according to the disclosure
Figure.
Fig. 2 is the signal for schematically showing the structure of imaging sensor of some exemplary embodiments according to the disclosure
Figure.
Fig. 3 A to 3D is the formation image schematically shown according to some exemplary embodiments of the disclosure
The schematic diagram in the section of the imaging sensor at some steps of the method for sensor.
Fig. 4 A to 4D is the formation image schematically shown according to some exemplary embodiments of the disclosure
The schematic diagram in the section of the imaging sensor at some steps of the method for sensor.
Fig. 5 A to 5C is the formation image schematically shown according to some exemplary embodiments of the disclosure
The schematic diagram in the section of the imaging sensor at some steps of the method for sensor.
Fig. 6 A to 6E is the formation image schematically shown according to some exemplary embodiments of the disclosure
The schematic diagram in the section of the imaging sensor at some steps of the method for sensor.
Note that same appended drawing reference is used in conjunction between different attached drawings sometimes in embodiments described below
It indicates same section or part with the same function, and omits its repeated explanation.In some cases, using similar mark
Number and letter indicate similar terms, therefore, once being defined in a certain Xiang Yi attached drawing, then do not needed in subsequent attached drawing pair
It is further discussed.
In order to make it easy to understand, position, size and range of each structure shown in attached drawing etc. etc. do not indicate practical sometimes
Position, size and range etc..Therefore, the disclosure is not limited to position, size and range disclosed in attached drawing etc. etc..
Specific embodiment
It is described in detail the various exemplary embodiments of the disclosure below with reference to accompanying drawings.It should also be noted that unless in addition having
Body explanation, the unlimited system of component and the positioned opposite of step, numerical expression and the numerical value otherwise illustrated in these embodiments is originally
Scope of disclosure.
Be to the description only actually of at least one exemplary embodiment below it is illustrative, never as to the disclosure
And its application or any restrictions used.That is, structure and method herein is to show in an exemplary fashion, for
The different embodiments of structures and methods in the bright disclosure.It will be understood by those skilled in the art, however, that they be merely illustrative can
Exemplary approach with the disclosure for being used to implement, rather than mode exhausted.In addition, attached drawing is not necessarily drawn to scale, it is some
Feature may be amplified to show the details of specific component.
Technology, method and apparatus known to person of ordinary skill in the relevant may be not discussed in detail, but suitable
In the case of, the technology, method and apparatus should be considered as authorizing part of specification.
It is shown here and discuss all examples in, any occurrence should be construed as merely illustratively, without
It is as limitation.Therefore, the other examples of exemplary embodiment can have different values.
It should be noted that the word "upper" in orientation described herein, "lower", "top", "bottom" etc., are for showing
It is described based on view direction (i.e. the surface for receiving light of imaging sensor is upward) in Fig. 1 and 2 of structure.And
In Fig. 3 A for showing step into 6E, the surface for receiving light of imaging sensor is downward (due in these steps
Rapid place is by the surface for being used to receive light of imaging sensor to operation of getting off), therefore, in the description referring to Fig. 3 A to 6E
Used in the word in orientation is described may be opposite with view direction shown in the drawings.For example, verbal description is " in semiconductor material
Dielectric layer 120 " is formed under the bed of material 110, but is located at semiconductor material for dielectric layer 120 shown in Fig. 3 A to 6E
On layer 110.
The present invention provides a kind of imaging sensors.Fig. 1 and Fig. 2 is schematically shown according to some of the disclosure respectively
The schematic diagram of the structure of the imaging sensor of exemplary embodiment.Imaging sensor according to an embodiment of the present invention includes pixel list
Member 20.Pixel unit 20 includes the photodiode 21 being formed in semiconductor material layer 110, is arranged in semiconductor material layer
Dielectric layer 120 under 110 is (for example, for wherein forming the gate structure of metal interconnecting piece 121 and/or transistor (not
Show) etc.) and the light for passing through semiconductor material layer 110 that is formed in dielectric layer 120 be directed to pixel unit
The light guide 22 of 20 photodiode 21.The bottom surface 22-1 of the separate semiconductor material layer 110 of light guide 22 is configured as
The light that bottom surface 22-1 is reached inside light guide 22 is reflected back inside light guide 22, side surface 22-2,22- of light guide 22
3 are configured as the light for reaching side surface 22-2,22-3 inside light guide 22 being reflected back inside light guide 22.Void in such as figure
Shown in line, the light a of the bottom surface 22-1 of light guide 22 is reached after semiconductor material layer 110, is reflected back by bottom surface 22-1
Inside light guide 22, so that these light are possible to be vectored back to again in the photodiode 21 of pixel unit 20, light a is avoided
Enter dielectric layer 120 after continuing across bottom surface 22-1.In addition, reaching light guide 22 after passing through semiconductor material layer 110
The light b of side surface 22-2,22-3, are reflected back inside light guide 22 by side surface 22-2,22-3, so that these light are possible to
Be vectored back in the photodiode 21 of pixel unit 20 again (as shared the same light c), avoid light b continue across side surface 22-2,
Enter dielectric layer 120 after 22-3.On the one hand enable in this way and light is not come back to by the light that photodiode 21 absorbs
Electric diode 21, i.e., it is possible that being absorbed again by photodiode 21, to improve the utilization rate of light；On the other hand reduce or
The light into dielectric layer 120 is avoided, so that light, which has been reduced or avoided, is reflected to optics caused by other pixel units
Crosstalk.
It should be appreciated that pixel unit 20 is a pixel list in pixel unit array included by imaging sensor
Member, imaging sensor obviously further include other pixel units.Shown in the drawings of the pixel unit adjacent with pixel unit 20
10,30 example as other pixel units.Pixel unit 10,30 respectively includes the light being formed in semiconductor material layer 110
Electric diode 11,31.Imaging sensor further includes colour filter 130 on the semiconductor material layer 110 and is located at colour filter
Microlens layer 140 on layer 130.Pixel unit 10,20,30 respectively include being formed in colour filter 13 among colour filter 130,
23,33 and the lenticule 14,24,34 that is formed among microlens layer 140.
The incident light d of pixel unit 20 enters photodiode 21 after successively passing through lenticule 24 and colour filter 23, not
After passing through semiconductor material layer 110 by the light (for example, it may be possible to being longer wavelengths of light) that photodiode 21 absorbs, into position
Dielectric layer 120 under semiconductor material layer 110.Since light guide 22 is located in dielectric layer 120, and with photoelectricity two
Pole pipe 21 with all or part of Chong Die (light guide in some embodiments in the plan view of the major surfaces in parallel of imaging sensor
22 can be located at the underface of photodiode 21), therefore, enter the light of dielectric layer 120 very across semiconductor material layer 110
Light guide 22 may be entered by the top surface 22-4 of light guide 22, and be directed into the bottom table of light guide 22 in light guide 22
Face 22-1 and side surface 22-2,22-3 (such as passing through one or many reflections, scattering etc.).It is led as described above, being directed into
The bottom surface 22-1 of light part 22 and light a, b of side surface 22-2,22-3 can be reflected back toward inside light guide 22, without by leading
The bottom surface 22-1 and side surface 22-2,22-3 of light part 22 are come out from light guide 22 to enter neighbouring pixel unit, such as
Pixel unit 10,30.
In some embodiments, the refractive index of the part at least adjacent to side surface 22-2,22-3 of light guide 22 is greater than electricity
The refractive index of the part by proximal face 22-2,22-3 of dielectric layer 120, so that side surface 22-2,22-3 of light guide 22
The light that side surface 22-2,22-3 are reached inside light guide 22 can be reflected back inside light guide 22 respectively.As this field
Known to technical staff, light reaches its interface with optically thinner medium from optically denser medium, when the angle of incidence is larger than a critical angle, entirely
Portion's light can be reflected back toward optically denser medium and is refracted into optically thinner medium without having light, i.e. generation total reflection phenomenon.Therefore, it configures
The refractive index of the part at least adjacent to side surface 22-2,22-3 of light guide 22 depends on proximal face 22- greater than dielectric layer 120
2, the refractive index of the part of 22-3 enables to the light for reaching side surface 22-2,22-3 inside light guide 22 when incidence angle is big
It is all reflected back inside light guide 22 when critical angle, without entering in the lesser dielectric layer 120 of refractive index.
Similar to the abovely, the refractive index of the part at least adjacent to bottom surface 22-1 of light guide 22 is greater than dielectric layer
The refractive index of the part of 120 close bottom surface 22-1, so that bottom surface 22-1 can will reach bottom inside light guide 22
The light of surface 22-1 is reflected back inside light guide 22.
In one implementation, the entirety of light guide 22 is formed of one material.Since light guide 22 does not need to absorb light, because
This light guide 22 can be formed by dielectric substance.In this case, the refractive index of the dielectric substance of light guide 22 is formed
Greater than the refractive index for the dielectric substance for forming dielectric layer 120.The refractive index of light guide 22 is more greater than the folding of dielectric layer 120
Rate is penetrated, the critical angle of total reflection phenomenon occurs with regard to smaller, more light can be reflected back toward inside light guide 22, fewer therewith
Light can enter dielectric layer 120, therefore, the effect of light guide 22 is better.In some embodiments, light guide 22 includes
Silicon nitride (refractive index is usually 2.02 or so), dielectric layer 120 include silica (refractive index is usually 1.46).
In some embodiments, light guide 22 includes the reflecting layer (figure on side surface 22-2,22-3 of light guide 22
1, it is not shown in 2, referring to the 22-6 in Fig. 6 E), reflecting layer is configured as the light that reflecting layer is reached inside light guide 22 is anti-
It is emitted back towards inside light guide 22, so that side surface 22-2,22-3 of light guide 22 reflect light back into light guide 22 with above-mentioned
Internal function.Therewith similarly, light guide 22 includes the reflecting layer 22-5 on the bottom surface 22-1 of light guide 22, reflection
Layer 22-5 is configured as the light for reaching reflecting layer 22-5 inside light guide 22 being reflected back inside light guide 22, so that leading
The bottom surface 22-1 of light part 22 has the function of above-mentioned reflect light back into inside light guide 22.These reflecting layer may each comprise
The Anti-reflective coating for the interference using light known and metallic reflector etc..
In some embodiments, as shown in Fig. 2, the bottom surface 22-1 of light guide 22 is formed as reclinate curved surface.Such as
This, compared to straight bottom surface shown in FIG. 1, reclinate bottom surface 22-1 also has while reflected light and will reflect
The light guide effect that light inwardly polymerize.This aspect can make side surface 22-2,22- of less reflected light arrival light guide 22
3, so that less light, which may pass through side surface 22-2,22-3, enters dielectric layer 120；On the other hand can make in bottom table
Angle of light when reflected light arrival side surface 22-2,22-3 of the same position of face 22-1 is bigger, therefore more light are in side
Can be totally reflected on the interface of surface 22-2,22-3 and dielectric layer 120, i.e., less light can pass through side surface 22-2,
22-3 enters dielectric layer 120.
In view of for same semiconductor material, the light penetration depth of the longer light of wavelength in a semiconductor material is more
Greatly.Therefore, the longer light of wavelength more may pass through semiconductor material layer 110 and enter the dielectric layer 120 being located under it.One
In a little embodiments, pixel unit 20 is used for the light of first wave length, and pixel unit 10 and/or 30 is used for the light of second wave length, wherein
First wave length is longer than second wave length.In some embodiments, first wave length is longer than second wave length and refers to, the institute that first wave length includes
There is first wave long value to be all larger than all second wave length values that second wave length includes.In some embodiments, first wave length is longer than
Two wavelength refer to that at least one first wave long value includes greater than second wave length in all first wave long values that first wave length includes
All second wave length values.In some embodiments, the pixel array of imaging sensor uses rgb color encoding scheme, pixel
Unit 20 is the pixel unit for being at least used for feux rouges, and pixel unit 10 and/or 30 is at least to be used in blue light and green light at least
One pixel unit.
Although adjacent with including the pixel unit 20 of light guide 22 in the pixel array of imaging sensor shown in the accompanying drawings
Pixel unit 10,30 do not include light guide, it will be understood by those skilled in the art that any of pixel unit 10,30 can
To be designed to include light guide as needed, semiconductor material layer 110 will be passed through in the pixel unit 10,30 and entered
The light of dielectric layer 120 under it is directed in the photodiode 11,31 of the pixel unit 10,30.In some implementations
In example, each pixel unit in the pixel array of imaging sensor can include light guide, in these cases, with figure
As the major surfaces in parallel of sensor plan view in, the light guide in each pixel unit can be with photodiode whole or portion
Point overlapping, metal interconnecting piece 121 in dielectric layer 120 can be located at except photodiode region (such as with it is floating
Set diffusion area overlapping, Chong Die with the region where transistor etc.), it partly Chong Die with photodiode (such as can also lead
In the case that light part and photodiode partly overlap).
Although dielectric layer 120 shown in the accompanying drawings is the layer of an entirety, it will be understood by those skilled in the art that dielectric
Layer 120 in fact may include multiple dielectric layers, can be formed with metal interconnecting piece 121 in each dielectric layer (more
The gate structure of transistor can also be formed in the dielectric layer of semiconductor material layer 110).Light guide 22 can be formed in
In one layer of dielectric layer, it can also be formed in multi-layer dielectric layer.
Although the top surface 22-4 of light guide 22 shown by attached drawing is not in contact with the lower surface of semiconductor material layer 110
(midfeather has to form the dielectric substance of dielectric layer 120), it will be understood by those skilled in the art that the top surface of light guide 22
22-4 can also directly be contacted with the lower surface of semiconductor material layer 110.In semiconductor material layer 110, by silicon, (refractive index is usual
Be 3.42 or so) formed in the case where, if silicon nitride (refractive index is usually 2.02 or so) formed light guide 22 top surface
Between 22-4 and semiconductor material layer 110 interval have the silica (refractive index is usually 1.46) to form dielectric layer 120, then with
It is not spaced silica to compare, since the refractive index of silica is less than the refractive index of silicon nitride, this makes from semiconductor material layer 110
More light that inside reaches the lower surface of semiconductor material layer 110 can be totally reflected back to the inside of semiconductor material layer 110 (because
Enter silicon nitride compared to from silicon, it is clear that the critical angle for entering silica from silicon is smaller).
Referring to the method for the formation imaging sensor of Fig. 3 A to 3D description according to some embodiments of the invention.It should infuse
Meaning, as described above, is operated in the lower surface of imaging sensor according to the method for the embodiment of the present invention.
As shown in Figure 3A, for the shape under the semiconductor material layer 110 for wherein forming photodiode 11,21,31
At dielectric layer 120.Dielectric layer 120 may include various known by dielectric under semiconductor material layer 110
The layer of formation, for example, being applied to the lower surface of semiconductor material layer 110 for preventing semiconductor material layer 110 to be oxidized
Dielectric layer, for wherein formed transistor gate structure dielectric layer, for forming metal interconnecting piece wherein
121 dielectric layer (such as interlevel dielectric layer of metal interconnecting layer) etc..In some embodiments, dielectric layer 120 includes
Silica.Forming dielectric layer 120 can complete according to any of suitable processing, for example, chemical vapor deposition
(CVD) processing forms silicon oxide layer etc..
Handled in the bottom surface of dielectric layer 120, at least partly removal dielectric layer 120 with imaging sensor
Major surfaces in parallel plan view in correspond to light guide 22 part, in dielectric layer 120 formed groove 122.It is formed
Groove 122 can be completed according to any of suitable processing, for example, first being formed on the bottom surface of dielectric layer 120
Mask layer is (including handling the photoresist layer being patterned by exposure development, being covered firmly by what etching processing was patterned
Film layer etc.), perform etching processing (for example, dry etching processing) then to form groove 122.Groove shown in Fig. 3 A
122 bottom does not reach the bottom surface of semiconductor material layer 110, this can be by semiconductor material layer 110 and dielectric layer
Etching stop layer is set between 120 to realize, can also be realized by controlling the time of etching processing.It should be appreciated that scheming
In step shown in 3A, the bottom of groove 122 can also reach the bottom surface of semiconductor material layer 110.The bottom of groove 122 is not
The bottom surface of semiconductor material layer 110 is reached in contrast, due between the bottom of groove 122 and semiconductor material layer 110
It is separated with dielectric substance between also, therefore the bad shadow to photodiode 21 can be especially to avoid double of conductor material layer 110
It rings.
As shown in figs. 3 b and 3 c, the filling dielectric material 123 in groove 122, and dielectric substance 123 do not fill up it is recessed
Slot 122, to form light guide 22.The refractive index of dielectric substance 123 is greater than the refractive index of material located around it, i.e. shape
At the refractive index of the dielectric substance of dielectric layer 120.In some embodiments, dielectric substance 123 includes silicon nitride.Recessed
Filling dielectric material 123 can be completed by any of suitable processing in slot 122, for example, in dielectric layer 120
Bottom surface carry out chemical vapor deposition process carry out deposited silicon nitride.It in some embodiments, can first as shown in Figure 3B, recessed
Dielectric substance 123 is filled up in slot 122, and patterned photoresist layer (such as then can use by etching processing again
And/or hard mask layer) remove the lower part for being filled in the dielectric substance in groove 122 123, as shown in Figure 3 C, to be formed
Light guide 22.In some embodiments, it is also possible to speed and time by control deposition processes, so that the dielectric of deposition
Material 123 does not fill up entire groove 122 inherently, to directly form light guide 22.
As shown in Figure 3D, in the groove 124 not being filled under light guide 22 filling dielectric material 125 to fill up
Groove 124, wherein the refractive index of dielectric substance 125 is less than refractive index (the i.e. refraction of dielectric substance 123 of light guide 22
Rate).In some embodiments, dielectric substance 125 is identical as the material of dielectric layer 120 is formed, such as is all silica.Through
It crosses after above-mentioned steps, the side surface that can make light guide 22 and bottom surface are because can will be from leading there are total reflection phenomenon
Side surface is reached inside light part 22 and the light of bottom surface is reflected back respectively inside light guide 22.Carrying out subsequent operation (such as shape
At the operation of colour filter 130 and microlens layer 140) after, imaging sensor as shown in Figure 1 can be formed.
Referring to the method for the formation imaging sensor of Fig. 4 A to 4D description according to some embodiments of the invention.According to this
The bottom surface for the light guide 22 in imaging sensor that the method for a little embodiments is formed is reclinate curved surface.This method first will
The corresponding position (see appended drawing reference 153) of mask layer 150 is formed as reclinate curved surface, then by the shape of mask layer 150
Shape is transferred on the dielectric substance 123 being filled in groove 122, to form the light guide with reclinate bottom surface
22.For simplicity, it omits and description the step of being repeated in previous embodiment.
Passing through step as mentioned before, filled up in groove 122 after dielectric substance 123 (as shown in Figure 3B),
The hard exposure mask 151 being patterned is formed on the bottom surface of dielectric layer 120, as shown in Figure 4 A.It can be by any of
Suitable processing, for example, first depositing one layer of hard mask material on the bottom surface of dielectric layer 120, is then being covered firmly to be formed
Photoresist layer is formed on membrane material and (such as being handled by exposure development) is patterned to photoresist layer, with sudden and violent
Expose the part that hard mask material corresponds to dielectric substance 123.Then to hard exposure mask material under the masking of photoresist layer
Material performs etching processing, to form hard exposure mask 151.In order to enable hard exposure mask 151 performs etching dielectric substance 123 subsequent
The step of in can effectively act as masking action, the material for forming hard exposure mask 151 should be different from dielectric substance 123.Example
Such as, when dielectric substance 123 includes silicon nitride, the material of hard exposure mask 151 may include titanium nitride (TiN).
As shown in Figure 4 B, the photoresist 152 of covering dielectric material 123 is formed under dielectric substance 123.It can
To be formed by any of suitable processing, for example, first applying one layer of photoresist on the bottom, then expose
Development treatment is patterned, and the part being located at immediately below dielectric substance 123 is only retained, and removes other parts.In Fig. 4 B
Shown in embodiment, only covering dielectric material 123 passes photoresist 152 without covering other regions with image
In the plan view of the major surfaces in parallel of sensor, photoresist 152 is completely coincident with dielectric substance 123.Those skilled in the art
Member is it should be understood that with the plan view of the major surfaces in parallel of imaging sensor, and the region where photoresist 152 is in addition to including
It can also include other regions except region where dielectric substance 123.For example, may include being located at dielectric substance
The sub-fraction region around region where 123, the curved surface which cannot form in the next steps greatly very much
Excessively gentle (curvature is too small) and expected effect is not achieved.In addition, it can include with being located at immediately below dielectric substance 123
Photoresist 152 is non-conterminous close or the photoresist that is not connected with, such as the photoresist under hard exposure mask 151
Agent, as long as these presence of photoresist that are non-conterminous close or being not connected with will not influence the curved surface formed in the next steps
Shape, etching processing in subsequent step will not be influenced.
As shown in Figure 4 C, at least photoresist 152 is heated, so that its reflux, which is formed, has curved table
The photoresist 153 in face.As shown in Figure 4 D, processing is performed etching, is selected higher and right to the etching rate of dielectric substance 123
The lower etching agent of etching rate of the material of hard exposure mask 151, to dielectric substance 123 under the masking action of hard exposure mask 151
It performs etching, so that the surface shape of photoresist 153 is transferred to dielectric substance 123, there is curved table to be formed
The light guide 22 in face.Later the step of, can be similar to shown in Fig. 3 D or Fig. 5 C and operate, and it is small that refractive index is filled in groove 124
In the dielectric substance of dielectric substance 123, the light guide 22 of albedo is all had to form side surface and bottom surface.
Referring to the method for the formation imaging sensor of Fig. 5 A to 5C description according to some embodiments of the invention.According to this
The light guide 22 in imaging sensor that the method for a little embodiments is formed includes the reflecting layer 22-5 on bottom surface.For simplicity
For the sake of, it omits and description the step of being repeated in previous embodiment.
After being performed etching by step as mentioned before to dielectric substance 123 (as shown in Figure 4 D), passing through
Reflecting layer 22-5 is formed on the bottom surface of the dielectric substance 123 of etching, to form light guide 22, as shown in Figure 5A.Reflection
Layer 22-5 may include metal.Forming reflecting layer 22-5 may include for example depositing or being electroplated one layer of metal layer 160.It then can be with
Removal is located at mask layer 150 and metal layer 160 under the bottom surface of dielectric layer 120, as shown in Figure 5 B.Later in groove
Filling dielectric material 125 in 124 all has the light guide 22 of albedo to form side surface and bottom surface, such as Fig. 5 C institute
Show.In this case, the bottom surface of light guide 22 has had albedo due to the presence of reflecting layer 22-5, is not required to
The refractive index for limiting dielectric substance 125 is less than the refractive index of dielectric substance 123.Certainly, those skilled in the art should manage
Solution, the refractive index of dielectric substance 125 might be less that the refractive index of dielectric substance 123, this makes not by reflecting layer 22-5
The light of reflection is likely due to total reflection and is reflected back toward inside light guide 22.
Fig. 5 A to 5C is described based on the light guide 22 with reclinate surface, and those skilled in the art should manage
Solution, can also form above-mentioned reflecting layer 22-5, and form step on the bottom surface of the light guide 22 with straight bottom surface
It is rapid also similar with above description.
Referring to the method for the formation imaging sensor of Fig. 6 A to 6E description according to some embodiments of the invention.According to this
The light guide 22 in imaging sensor that the method for a little embodiments is formed includes the reflecting layer 22-6 on its side surface.For letter
Just it for the sake of, omits and description the step of being repeated in previous embodiment.
After forming groove 122 by step as mentioned before (as shown in Figure 3A), the shape on the side wall of groove 122
At reflecting layer 170, as shown in Figure 6A.Reflecting layer 170 may include metal.Formed reflecting layer 170 may include for example deposition or
One layer of metal layer is electroplated.Part due to needing for be located in reflecting layer 170 122 bottom of groove removes, as shown in Figure 6B, so that
Light can be entered in light guide 22 to be formed, reflecting layer 170 can be located at 122 bottom of groove by etching processing
Partial etching falls.The etching processing needs the masking action using mask layer 150.Mask layer 150 may include by patterning
Photoresist and/or hard exposure mask 154 (being labeled collectively as 154), need the part that etches to expose.Etching processing can be with
Stop at dielectric layer 120.
As shown in figures 6 c and 6d, deposition is used to form the dielectric substance 180 of light guide 22, then by dielectric substance
The 180 part removal being located on dielectric layer 120, to form the dielectric substance 123 being filled in groove 122.Reflection
The part of the side surface positioned at dielectric substance 123 of layer 170 is formed as reflecting layer 171.It is recessed to being located at due to also needing later
The lower part of material in slot 122 performs etching processing, and therefore, in this step, dielectric substance 123 can fill up entire groove
122。
As illustrated in fig. 6e, the lower part in dielectric substance 123 and reflecting layer 171 is removed.It can be initially formed mask layer 150,
It includes needing to etch to expose by patterned photoresist and/or hard exposure mask 155 (being labeled collectively as 155)
Part；Then the lower part that dielectric substance 123 and reflecting layer 171 are removed by etching processing, so that being formed in side surface has
The light guide 22 of reflecting layer 22-6.Later the step of, can be similar to shown in Fig. 3 D or Fig. 5 C and operate, and fill in groove 124
Refractive index is less than the dielectric substance of dielectric substance 123, all has the leaded light of albedo to form side surface and bottom surface
Part 22.
Although the imaging sensor of pixel region is only schematically shown in the attached drawing of the disclosure in sectional view
Structure, those skilled in the art can obtain the entirety of imaging sensor involved in the disclosure based on the content that the disclosure is recorded
Structure and forming method.
Word " A or B " in specification and claim includes " A and B " and " A or B ", rather than is exclusively only wrapped
Include " A " or only include " B ", unless otherwise specified.
In the word "front", "rear" in specification and claim, "top", "bottom", " on ", " under " etc., if deposited
If, it is not necessarily used to describe constant relative position for descriptive purposes.It should be appreciated that the word used in this way
Language be in appropriate circumstances it is interchangeable so that embodiment of the disclosure described herein, for example, can in this institute
It is operated in those of description show or other other different orientations of orientation.
As used in this, word " illustrative " means " be used as example, example or explanation ", not as will be by
" model " accurately replicated.It is not necessarily to be interpreted than other implementations in any implementation of this exemplary description
It is preferred or advantageous.Moreover, the disclosure is not by above-mentioned technical field, background technique, summary of the invention or specific embodiment
Given in go out theory that is any stated or being implied limited.
As used in this, word " substantially " means comprising the appearance by the defect, device or the element that design or manufacture
Any small variation caused by difference, environment influence and/or other factors.Word " substantially " also allows by ghost effect, makes an uproar
Caused by sound and the other practical Considerations being likely to be present in actual implementation with perfect or ideal situation
Between difference.
In addition, the description of front may be referred to and be " connected " or " coupling " element together or node or feature.Such as
It is used herein, unless explicitly stated otherwise, " connection " mean an element/node/feature and another element/node/
Feature is being directly connected (or direct communication) electrically, mechanically, in logic or in other ways.Similarly, unless separately
It clearly states outside, " coupling " means that an element/node/feature can be with another element/node/feature with direct or indirect
Mode link mechanically, electrically, in logic or in other ways to allow to interact, even if the two features may
It is not directly connected to be also such.That is, " coupling " is intended to encompass the direct connection and indirectly of element or other feature
Connection, including the use of the connection of one or more intermediary elements.
In addition, just to the purpose of reference, can with the similar terms such as " first " used herein, " second ", and
And it thus is not intended to limit.For example, unless clearly indicated by the context, be otherwise related to structure or element word " first ", "
Two " do not imply order or sequence with other such digital words.
It should also be understood that one word of "comprises/comprising" as used herein, illustrates that there are pointed feature, entirety, steps
Suddenly, operation, unit and/or component, but it is not excluded that in the presence of or increase one or more of the other feature, entirety, step, behaviour
Work, unit and/or component and/or their combination.
In the disclosure, therefore term " offer " " it is right to provide certain from broadly by covering all modes for obtaining object
As " including but not limited to " purchase ", " preparation/manufacture ", " arrangement/setting ", " installation/assembly ", and/or " order " object etc..
It should be appreciated by those skilled in the art that the boundary between aforesaid operations is merely illustrative.Multiple operations
It can be combined into single operation, single operation can be distributed in additional operation, and operating can at least portion in time
Divide and overlappingly executes.Moreover, alternative embodiment may include multiple examples of specific operation, and in other various embodiments
In can change operation order.But others are modified, variations and alternatives are equally possible.Therefore, the specification and drawings
It should be counted as illustrative and not restrictive.
In addition, embodiment of the present disclosure can also include following example:
1. a kind of imaging sensor, which is characterized in that including the first pixel unit, first pixel unit includes:
The photodiode being formed in semiconductor material layer；
Dielectric layer under the semiconductor material layer is set；And
The light for passing through the semiconductor material layer being formed in the dielectric layer is directed to the photoelectricity two
The light guide of pole pipe, the bottom surface far from the semiconductor material layer of the light guide is configured as will be out of described light guide
The light that portion reaches the bottom surface is reflected back inside the light guide, and the side surface of the light guide is configured as to lead from described
The light that the side surface is reached inside light part is reflected back inside the light guide.
2. the imaging sensor according to 1, which is characterized in that the portion at least adjacent to the side surface of the light guide
The refractive index divided is greater than the refractive index of the part close to the side surface of the dielectric layer.
3. the imaging sensor according to 1, which is characterized in that the dielectric layer includes the first dielectric substance, institute
Stating light guide includes the second dielectric substance, and the refractive index of second dielectric substance is greater than first dielectric substance
Refractive index.
4. the imaging sensor according to 1, which is characterized in that the light guide includes silicon nitride, the dielectric layer
Including silica.
5. the imaging sensor according to 1, which is characterized in that the light guide includes the side table positioned at the light guide
The first reflecting layer on face, first reflecting layer are configured as that first reflecting layer will be reached inside the light guide
Light is reflected back inside the light guide.
6. the imaging sensor according to 5, which is characterized in that first reflecting layer includes metal.
7. the imaging sensor according to 1, which is characterized in that the portion at least adjacent to the bottom surface of the light guide
The refractive index divided is greater than the refractive index of the part close to the bottom surface of the dielectric layer.
8. the imaging sensor according to 1, which is characterized in that the light guide includes the bottom table positioned at the light guide
The second reflecting layer on face, second reflecting layer are configured as that second reflecting layer will be reached inside the light guide
Light is reflected back inside the light guide.
9. the imaging sensor according to 8, which is characterized in that second reflecting layer includes metal.
10. the imaging sensor according to 1, which is characterized in that the bottom surface is reclinate curved surface.
11. the imaging sensor according to 1, which is characterized in that the dielectric layer is multilayer, and the light guide is formed
In one or more layers described dielectric layer.
12. the imaging sensor according to 1, which is characterized in that the light guide and the photodiode with institute
It states and is overlapped in the plan view of the major surfaces in parallel of imaging sensor.
13. the imaging sensor according to 1, which is characterized in that described image sensor further includes the second pixel unit,
First pixel unit is used for the light of first wave length, and second pixel unit is used for the light of second wave length, wherein described the
One wavelength is longer than second wave length, and second pixel unit does not include the light guide.
14. the imaging sensor according to 13, which is characterized in that the first wave length includes one or more first waves
Long value, the second wave length include one or more second wave length values, wherein in one or more of first wave long values at least
There is a first wave long value to be greater than whole second wave length values included by the second wave length.
15. the imaging sensor according to 1, which is characterized in that the pixel array of described image sensor uses RGB color
Color encoding scheme, first pixel unit include the pixel unit for feux rouges.
16. the imaging sensor according to 13, which is characterized in that the pixel array of described image sensor uses RGB
Color encoding scheme, first pixel unit include the pixel unit for feux rouges, and second pixel unit includes being used for
The pixel unit of blue light.
17. the imaging sensor according to 1, which is characterized in that the dielectric layer is mutual for forming metal wherein
The even gate structure of part and/or transistor.
18. a kind of method for forming imaging sensor characterized by comprising
For forming dielectric layer under the semiconductor material layer for wherein forming photodiode；And
It is formed in the dielectric layer and is directed to two pole of photoelectricity for passing through the light of the semiconductor material layer
The light guide of pipe, the bottom surface far from the semiconductor material layer of the light guide is configured as will be inside the light guide
The light for reaching the bottom surface is reflected back inside the light guide, and the side surface of the light guide is configured as will be from the leaded light
The light that the side surface is reached inside part is reflected back inside the light guide.
19. the method according to 18, which is characterized in that the dielectric layer includes the first dielectric substance, described to lead
Light part includes the second dielectric substance, and the refractive index of second dielectric substance is greater than the refraction of first dielectric substance
Rate, wherein the light guide is formed in the dielectric layer includes:
Handled in the bottom surface of the dielectric layer, at least partly remove the dielectric layer with described image
Correspond to the part of the light guide in the plan view of the major surfaces in parallel of sensor, it is recessed to be formed in the dielectric layer
Slot；
Fill second dielectric substance in the groove, and second dielectric substance do not fill up it is described recessed
Slot；And
Described to fill up not by filling third dielectric substance in the groove that second dielectric substance fills up
Groove, wherein the refractive index of the third dielectric substance is less than the refractive index of second dielectric substance.
20. the method according to 19, which is characterized in that form the light guide in the dielectric layer further include:
After forming the groove and before filling second dielectric substance, in the side wall of the groove
The first reflecting layer of upper formation, first reflecting layer are configured as that first reflecting layer will be reached inside the light guide
Light is reflected back inside the light guide.
21. the method according to 20, which is characterized in that forming first reflecting layer includes: in the side of the groove
Metal layer is formed on wall.
22. the method according to 19, which is characterized in that form the light guide in the dielectric layer further include:
After filling second dielectric substance and before filling the third dielectric substance, filled out
It fills on the bottom surface of second dielectric substance in the groove and forms the second reflecting layer, second reflecting layer is matched
It is set to and the light for reaching second reflecting layer inside the light guide is reflected back inside the light guide.
23. the method according to 22, which is characterized in that formed second reflecting layer include: be filled in it is described
Metal layer is formed on the bottom surface of second dielectric substance in groove.
24. the method according to 19, which is characterized in that form the light guide in the dielectric layer further include:
After filling second dielectric substance and before filling the third dielectric substance, it will be filled out
The bottom surface of second dielectric substance filled in the groove is formed as reclinate curved surface.
25. the method according to 15, which is characterized in that the third dielectric substance and first dielectric substance
It is identical.
26. the method according to 15, which is characterized in that the dielectric layer for forming metal interconnecting piece wherein
And/or the gate structure of transistor.
Although being described in detail by some specific embodiments of the example to the disclosure, the skill of this field
Art personnel it should be understood that above example merely to be illustrated, rather than in order to limit the scope of the present disclosure.It is disclosed herein
Each embodiment can in any combination, without departing from spirit and scope of the present disclosure.It is to be appreciated by one skilled in the art that can be with
A variety of modifications are carried out without departing from the scope and spirit of the disclosure to embodiment.The scope of the present disclosure is limited by appended claims
It is fixed.
Claims (10)
1. a kind of imaging sensor, which is characterized in that including the first pixel unit, first pixel unit includes:
The photodiode being formed in semiconductor material layer；
Dielectric layer under the semiconductor material layer is set；And
The light for passing through the semiconductor material layer being formed in the dielectric layer is directed to the photodiode
Light guide, the light guide far from the semiconductor material layer bottom surface be configured as by inside the light guide to
Light up to the bottom surface is reflected back inside the light guide, and the side surface of the light guide is configured as will be from the light guide
The light that inside reaches the side surface is reflected back inside the light guide.
2. imaging sensor according to claim 1, which is characterized in that the light guide at least adjacent to the side surface
Part refractive index be greater than the dielectric layer close to the side surface part refractive index.
3. imaging sensor according to claim 1, which is characterized in that the dielectric layer includes the first dielectric material
Material, the light guide include the second dielectric substance, and the refractive index of second dielectric substance is greater than first dielectric
The refractive index of material.
4. imaging sensor according to claim 1, which is characterized in that the light guide includes silicon nitride, and the electricity is situated between
Matter layer includes silica.
5. imaging sensor according to claim 1, which is characterized in that the light guide includes being located at the light guide
The first reflecting layer on side surface, first reflecting layer are configured as that first reflection will be reached inside the light guide
The light of layer is reflected back inside the light guide.
6. imaging sensor according to claim 5, which is characterized in that first reflecting layer includes metal.
7. imaging sensor according to claim 1, which is characterized in that the light guide at least adjacent to the bottom surface
Part refractive index be greater than the dielectric layer close to the bottom surface part refractive index.
8. imaging sensor according to claim 1, which is characterized in that the light guide includes being located at the light guide
The second reflecting layer on bottom surface, second reflecting layer are configured as that second reflection will be reached inside the light guide
The light of layer is reflected back inside the light guide.
9. imaging sensor according to claim 8, which is characterized in that second reflecting layer includes metal.
10. imaging sensor according to claim 1, which is characterized in that the bottom surface is reclinate curved surface.
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Application publication date: 20190628 |